Antenna case for smartphones and wireless terminals

ABSTRACT

A portable accessory for preventing death grip of a hand-held apparatus and improving radio wave transmission and reception of the hand-held apparatus. The portable accessory includes an inductive signal amplifying circuit including: a radio transmission/radio unit that transmits or receives radio waves; a capacitive coupled unit that is capacitively coupled with an antenna mounted in the hand-held apparatus; and an impedance matching unit that connects the radio wave transmission/reception unit and the capacitive coupled unit and transmits radio waves.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2012-0013331, filed on Feb. 9, 2012, and 10-2011-107713 filed on Dec.20, 2011, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an accessory for improving radio wavetransmission and reception in a hand-held apparatus such as asmartphone, a tablet, a personal digital assistant (PDA), and a laptopcomputer, and more particularly, to a protection case and a protectionfilm that improve radio wave transmission and reception.

2. Description of the Related Art

Along with the rapid increase in use of hand-held apparatuses such assmartphones and tablets, radio wave transmission and receptionconditions in the hand-held apparatuses are an important issue. Inparticular, if a portion of a smartphone where an antenna is mounted isheld by the hand during a telephone conversation or data communication,death grip, which refers to a decrease in call quality or call drops,and an increase in battery consumption may occur.

SUMMARY OF THE INVENTION

The present invention provides a portable accessory that prevents deathgrip of a hand-held apparatus such as a smartphone without having todeform the hand-held apparatus, and increases sensitivity of radio wavetransmission and reception by the hand-held apparatus.

According to an aspect of the present invention, there is provided aportable accessory for preventing death grip occurring recently inhand-held apparatuses or the like, and improving radio wave transmissionand reception.

The portable accessory may be, for example, a protection case or aprotection film. For example, for smartphones, the portable accessorymay be implemented as a smartphone protection case or a protection film.

In addition, other accessories of various shapes and forms for hand-heldapparatuses besides smartphones may also be used. For example, aportable accessory having various shapes such as a striped shape, arectangular shape, various figures, a three-dimensional shape, a twistedshape, an animal or plant-like shape, or the like may be used.

Also, the portable accessory may be implemented as, for example, asticker, a protection film, or a protection case that may be attached ona hand-held apparatus, or in the form of a doll, a string, a grip, or acase.

Accordingly, according to the embodiments of the present invention, byusing a portable accessory for a hand-held apparatus, radio wavestransmission and reception may be improved without changing internal andexternal structures of the hand-held apparatus, and death grip may beprevented.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a schematic diagram of death grip (or call drop) whichrecently frequently occurs;

FIG. 2 is a diagram illustrating a structure in which radio waves aretransmitted or received via an antenna of a portable wireless terminal;

FIG. 3 is a schematic diagram illustrating a method of improving radiowave transmission and reception by a mobile phone by mounting a mobilephone protection case, according to an embodiment of the presentinvention;

FIG. 4 is a schematic diagram illustrating a method of improving radiowave transmission and reception via capacitive coupling between anantenna mounted in a mobile phone protection case and an antenna mountedin a mobile phone, according to an embodiment of the present invention;

FIG. 5 is a detailed diagram of FIG. 4;

FIGS. 6A and 6B illustrate a position of a capacitive coupled unitaccording to an embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating a method of forming acapacitive coupled unit of an accessory according to permittivity of amaterial of an outer portion of a mobile phone, according to anembodiment of the present invention;

FIG. 8 is a schematic diagram illustrating an inductive signalamplifying circuit mounted in a mobile phone protection case, accordingto an embodiment of the present invention; and

FIG. 9 is a schematic diagram illustrating an inductive signalamplifying circuit covered with a protection film, according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown.

FIG. 1 is a schematic diagram of death grip (or call drop) whichrecently frequently occurs.

If a smartphone user grasps a lower portion 100 in which an antenna ismounted during a call via a smartphone or during data communication viathe smartphone, the call may be dropped or quality of the call maydecrease, which may increase battery consumption.

In other words, hand-effects according to how the user grips thesmartphone are increasing, and if the user wraps his/her hand around thesmartphone, an operating range of an antenna may shift or dielectricloss may occur, thereby reducing gains of the antenna. In order to solvethis problem, a bumper is applied. However, even when a bumper is used,antenna gains are still short.

FIG. 2 is a diagram illustrating a structure in which radio waves aretransmitted or received via an antenna 210 of a portable wirelessterminal.

As mobile wireless terminals have been reduced in size and becomethinner, a size of the antenna 210 mounted in the mobile wirelessterminals has also been reduced. For example, the antenna 210 may have asize that fits into the lower portion 100 of the smartphone illustratedin FIG. 1.

The antenna 210 is mounted in a main body case 220 of a hand-heldapparatus such as a smartphone, a personal digital assistant (PDA), apersonal multimedia player (PMP), a tablet, etc. to transmit or receiveradio waves to or from the outside. However, as the antenna 210 becomescompact, if the lower portion 100 where the antenna 210 is mounted isheld by the user's hand, as illustrated in FIG. 1, call quality maydecrease remarkably and a battery may be consumed rapidly.

FIG. 3 is a schematic diagram illustrating a method of improving radiowave transmission and reception by a mobile phone by mounting a mobilephone protection case, by which depth grip is prevented, according to anembodiment of the present invention.

It is to note that according to an embodiment of the presentapplication, a portable accessory may be implemented as a protectioncase or a protection film, and other accessories of other shapes andforms for hand-held apparatuses besides smartphones may also be used.For example, an accessory having various shapes such as a striped shape,a rectangular shape, various figures, a three-dimensional shape, atwisted shape, an animal or plant-like shape, a doll, a string, a grip,a case, etc. may be used.

In addition, the accessory may be implemented as an adhesive type or adetachable type accessory such as a sticker, a protection film, or aprotection case. Also, the accessory may be implemented, for example, asa radio frequency identification (RFID) tag.

According to an embodiment of the present invention, by using anaccessory for a hand-held apparatus, radio wave transmission andreception may be improved without modifying internal and externalstructures of the hand-held apparatus and death grip may be prevented.

FIG. 3 is a diagram illustrating a mobile phone protection case forpreventing death grip that recently occurs in smartphones, according toan embodiment of the present invention.

According to an embodiment of the present invention, an antenna mountedin a mobile phone protection case and an antenna mounted in a smartphoneare capacitively coupled, thereby facilitating transmission or receptionof radio waves, reducing signal distortion, and preventing death grip.

The mobile phone protection case according to the current embodiment ofthe present invention may be used for any portable wireless terminalsthat include an antenna that may be capacitively coupled with an antennamounted in a mobile phone protection film.

Referring to FIG. 3, an antenna 310 in a mobile wireless terminal isdisposed to be in capacitive coupling with an antenna mounted in amobile phone protection case or an inductive signal amplifying circuit400.

FIG. 4 is a schematic diagram illustrating a method of improving radiowave transmission and reception via capacitive coupling between anantenna mounted in a mobile phone protection case and an antenna mountedin a mobile phone, according to an embodiment of the present invention.FIG. 5 is a detailed diagram of FIG. 4. The method is described withreference to FIGS. 4 and 5.

The inductive signal amplifying circuit 400 mounted in the mobile phoneprotection case is disposed to form capacitive coupling with the antenna310 mounted in the mobile phone. In this case, the capacitive couplingbetween the inductive signal amplifying circuit 400 mounted in themobile phone protection case and the antenna 310 mounted in the mobilephone may vary according to permittivity of a material of an outerportion of the mobile phone. This will be described with reference toFIG. 7.

The inductive signal amplifying circuit 400 mounted in the mobile phoneprotection case may be disposed as broad as possible on a surface areaof an inner portion of the mobile phone protection case. For example, acircuit may be designed over a surface area as broad as possible so asto surround an external angle of the inner portion of the mobile phoneprotection case, thereby increasing an area for transmitting orreceiving radio waves. In addition, a circuit may be arranged to extendoutside the mobile phone protection case or in a three-dimensionalmanner.

As illustrated in FIG. 4, capacitive coupling between the inductivesignal amplifying circuit 400 and the antenna (FIG. 3,310) in the mobilephone is obtained, and as radio waves are transmitted or received over alarge area of the inductive signal amplifying circuit 400, the area forradio wave transmission and reception may be increased.

Referring to FIG. 5, the inductive signal amplifying circuit 400 mountedin the mobile phone protection case may include a radio wavetransmission/reception unit 430, a capacitive coupled unit 410, and animpedance matching unit 420. An example of the radio wavetransmission/reception unit 430 is an antenna. Also, the radio wavetransmission/reception unit 430 may transmit or receive radio waves viaWifi or radio frequency (RF).

The capacitive coupled unit 410 in the mobile phone protection case maybe disposed in a position corresponding to the built-in antenna 310 inthe mobile phone 310. For example, when the antenna 310 in the mobilephone is disposed in the lower part of the mobile phone, the capacitivecoupled unit 410 may also be disposed in the lower part of the mobilephone protection case so as to adjust a coupling interval of thecapacitive coupling.

The impedance matching unit 420 induces flow of radio waves over a metalsurface, and may transmit radio waves received from the radio wavetransmission/reception unit 430 to the capacitive coupled unit 410 ormay transmit radio waves of the capacitive coupled unit 410 to the radiowave transmission/reception unit 430.

An impedance line 421 connects the radio wave transmission/receptionunit 430 and the capacitive coupled unit 410. The impedance matchingunit 420 includes a portion where the impedance line 421 and the radiowave transmission/reception unit 430 meet and a portion where theimpedance line 421 and the capacitive coupled unit 410 meet, and radiowave signals transmit without any loss along an impedance line whenimpedance matching is provided.

In particular, although the impedance matching unit 420 may preferablybe disposed so as to surround a surface in the mobile phone protectioncase as broad as possible, if the impedance line 421 is too long, thefunction of a device in the mobile phone may degrade or radio waves maybe lost. Thus, the impedance line 421 may preferably be short, and thereis no need for a trade-off between the broad surface area in the mobilephone protection case and loss of radio waves of the impedance line 420.

According to an embodiment of the present invention, a protection filmmay be mounted over the inductive signal amplifying circuit 400 mountedin the mobile phone protection case. For example, a thin radiowave-transmissive dielectric having a thickness of 0.5 mm or less may beused as the protection film.

The mobile phone protection case may preferably be formed of adielectric such as plastic or rubber, and may be not too thick so thatloss of radio waves during transmission or reception of radio waves viathe inductive signal amplifying circuit 400 may be reduced.

While the inductive signal amplifying circuit 400 mounted in the mobilephone protection case has been described, the inductive signalamplifying circuit 400 may also be mounted in other various positions.

According to an embodiment of the present invention, the inductivesignal amplifying circuit 400 may have a structure in which a flexibleprint circuit board (FPCB) on which an amplifying circuit is designed isattached to a protection case for smartphones, etc. This will bedescribed with reference to FIGS. 8 and 9.

Alternatively, the inductive signal amplifying circuit 400 may beattached on a rear surface of a mobile phone in the form of an adhesiveprotection film.

Alternatively, the inductive signal amplifying circuit 400 may beprinted directly on a mobile phone protection case by using a silkprinting method using a highly reflective coating agent (dielectricpigment), thereby increasing transmission/reception efficiency.

FIGS. 6A and 6B illustrate a position of a capacitive coupled unitaccording to an embodiment of the present invention.

The antenna 310 in the mobile phone (see FIG. 5) and the capacitivecoupled unit 410 (see FIG. 5) in the mobile phone protection case mayarranged in a non-contact manner with a dielectric that is verticallydisposed therebetween.

Preferably, the capacitive coupled unit may be disposed in a mobilephone protection case to correspond to a position of the antenna mountedin the mobile phone. Also, so that radio waves may be induced betweenthe antenna mounted in the mobile phone and the capacitive coupled unitin the mobile phone protection case, a coupling interval may be adjustedaccording to frequencies.

FIG. 7 is a schematic diagram illustrating a method of forming acapacitive coupled unit of an accessory according to permittivity of amaterial of an outer portion of a mobile phone, according to anembodiment of the present invention.

Permittivity of dielectrics varies according to types of mobile phones.In general, the higher the permittivity, the lower the radio wavetransmission rate, and thus, plastic is frequently used to form an outerportion of a mobile phone (e.g., a mobile phone case).

According to an embodiment of the present invention, a matching circuitused inside a mobile phone case (or an inductive signal amplifyingcircuit) is implemented in various manners according to permittivity ofa material of an outer portion of a mobile phone. A matching circuitincludes a radio wave transmitting unit (not shown), a capacitivecoupled unit (not shown), and an impedance matching unit (not shown).

That is, permittivity of a capacitive coupled unit used in an innercircuit of a mobile phone protection case is adjusted according topermittivity of the material of an outer portion of a mobile phone so asto obtain a maximum capacitive coupling. When manufacturing a case usinga material having a high permittivity, since a frequency transmits thematerial and thus an effective wavelength is shortened, a compactantenna may be used, but on the other hand, an application frequencybandwidth is reduced and frequency loss is usually increased.

According to an embodiment of the present invention, a material having apermittivity ∈_(r) of about 2.0 to 3.5 may be used to minimize frequencyloss. Although, for example, Teflon may be used to reduce manufacturingcosts, polycarbonates having a high intensity may also be used with athin thickness so as to minimize loss of radio waves.

Also, according to an embodiment of the present invention, an antenna ora capacitive coupling device uses a ¼ wavelength, and in this case, aneffective dielectric constant is as expressed in Equation 1.

$\begin{matrix}{{\sqrt{ɛ_{e}} = {1 + {\frac{a}{b}\left( {{\overset{\_}{a}}_{1} - {{\overset{\_}{b}}_{1}\ln \; \frac{W}{b}}} \right)\left( {\sqrt{ɛ_{e}} - 1} \right)}}}{where}{{{\overset{\_}{a}}_{1} = \left( {0.5173 - {0.1515\ln \; \frac{a}{b}}} \right)^{4}},\; {{\overset{\_}{b}}_{1} = \left( {0.3092 - {0.1047\ln \; \frac{a}{b}}} \right)^{4}},}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

∈_(e) denotes effective permittivity, ∈_(r) denotes permittivity of amaterial, a denotes a substrate thickness, b denotes a distance, Wdenotes a width of an antenna pattern, and f denotes a frequency.

Equation 2 shows a length of an effective wavelength using an effectivepermittivity.

$\begin{matrix}{{lengthofeffectivewavelength} = \frac{lengthofwavelength}{\sqrt{ɛ_{r}}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Equation 3 shows a relationship between an effective permittivity andpermittivity of a material.

$\begin{matrix}{{\sqrt{ɛ_{e}} = {1 + {\frac{a}{b}\left( {a_{1} - {b_{1}\ln \; \frac{W}{b}}} \right)^{4}}}}{a_{1} = \left( {0.5173 - {0.1515\ln \; \frac{a}{b}}} \right)^{4}}{b_{1} = \left( {0.3092 - {0.1047\ln \; \frac{a}{b}}} \right)^{4}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

FIG. 8 is a schematic diagram illustrating an inductive signalamplifying circuit mounted in a mobile phone protection case, accordingto an embodiment of the present invention.

An impedance matching unit of the inductive signal amplifying circuit isformed to surround a surface of an inner portion of the mobile phoneprotection case as broad as possible but a here short impedance line isincluded.

According to an embodiment of the present invention, an impedancematching unit 820 of the inductive signal amplifying circuit may connecta radio wave transmission/reception unit 810 and a capacitive coupledunit 830, and function as an impedance line for extending impedancematching by extending the radio wave transmission/reception unit 810 atthe same time.

Although the radio wave transmission/reception unit 810 and theimpedance matching unit 820 are separated in the current embodiment ofthe present invention, the embodiment of the present invention is notlimited thereto.

FIG. 9 is a schematic diagram illustrating an inductive signalamplifying circuit covered with a protection film, according to anembodiment of the present invention.

In a wireless terminal including batteries for transmitting or receivingfrequencies via an antenna (e.g., smartphones or hand-held apparatuses),a lifespan of the batteries may vary according to radio environmentsbecause data throughput and signal output power vary according to amodulation method of a wireless modem mounted in the wireless terminal.That is, if a wireless signal having a high intensity is received,communication is performed at a high speed and a low output, and if awireless signal having a low intensity is received, communication isperformed at a high output and a low speed. That is, if effectiveisotropically radiated power (EIRP) of the wireless terminal is high, acommunication success rate even in a low-frequency signal environment isincreased.

EIRP refers to the amount of power in a condition in which peak powerpoint of an antenna is assumed as radiating in all directions. EIRP iscalculated by multiplying an input power by an antenna gain and is usedas an index for collectively determining a power-gain performance of atransmission/reception system based on an omni-directional antenna. Indetail, if power of 30 dBm is radiated from a predetermined antenna anda gain thereof is 10 dBi, the EIRP is 30+10=40 dBm.

According to the embodiments of the present invention, to increase anantenna gain of the EIRP, which is the total sum of the radiated powerof the predetermined antenna and the antenna gain, the lifespan of thebatteries may be increased by reducing an output power of an activedevice of the wireless communication system in which battery consumptionis high and by increasing the antenna gain of the antenna, which is apassive device where a battery is not consumed.

In addition, according to the embodiments of the present invention, anefficiency of transmission output is improved by improving a voltagestanding wave ratio (VSWR) of basically built-in antenna. In otherwords, a VSWR of an antenna case used in smartphones or wirelessterminals according to the embodiments of the present invention isreduced to be lower than that of conventional antennas such that anoutput of waves transmitted from the wireless terminals does not returnbut is radiated in the air with a high efficiency, thereby reducingpower loss in a low output power.

According to the embodiments of the present invention, intensity ofradio waves that are received or transmitted by a mobile phone may beincreased by using a portable accessory. In addition, according to anembodiment of the present invention, by increasing a surface area overwhich radio waves may be transmitted or received, by using the portableaccessory, death grip of a smartphone may be prevented.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

What is claimed is:
 1. An antenna case for smartphones and wirelessterminals comprising an inductive signal amplifying circuit, wherein theinductive signal amplifying circuit comprises: a radiotransmission/radio unit that transmits or receives radio waves; acapacitive coupled unit that is capacitively coupled with an antennamounted in a hand-held apparatus; and an impedance matching unit thatconnects the radio wave transmission/reception unit and the capacitivecoupled unit and transmits radio waves.
 2. The antenna case of claim 1,wherein the capacitive coupled unit is disposed at a position tocorrespond to the antenna mounted in the hand-held apparatus in theinductive signal amplifying circuit.
 3. The antenna case of claim 1,wherein the capacitive coupled unit is capacitively coupled with theantenna mounted in the hand-held apparatus in a non-contact manner witha dielectric disposed therebetween.
 4. The antenna case of claim 3,wherein the dielectric is formed of a material that forms an outerportion of the hand-held apparatus.
 5. The antenna case of claim 1,wherein permittivity of the capacitive coupled unit is adjustedaccording to a material of an outer portion of the mobile phone suchthat a maximum capacitive coupling between the capacitive coupled unitand the antenna mounted in the hand-held apparatus
 6. The antenna caseof claim 1, wherein the portable accessory is a mobile phone protectioncase.
 7. The antenna case of claim 1, wherein the portable accessory isa protection film.
 8. The antenna case of claim 6, wherein the inductivesignal amplifying circuit is attachable to the mobile phone protectioncase.
 9. The antenna case of claim 6, wherein the inductive signalamplifying circuit is printed directly on the mobile phone protectioncase by using a silk printing method.
 10. The antenna case of claim 6,wherein the inductive signal amplifying circuit is printed directly onthe protection film by using a silk printing method.
 11. The antennacase of claim 6, wherein the impedance matching unit is formed on asurface of an inner portion of the mobile phone protection case as broadas possible.